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  4. Slot called twice when button pressed

Slot called twice when button pressed

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  • P PetQter
    11 Apr 2019, 05:22

    Like I described in above posts - I did not use my own connect() I use designer so it is auto-connected. To exclude some other things done in the past I created new pushButton with slot for debugging purpose and behavior is the same.
    I use notebook with USB mouse I have not touch screen. Stack screenshots:

    0_1554960102132_Stack1.jpg
    0_1554960128031_Stack2.jpg
    0_1554960149075_Stack3.jpg

    J Offline
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    J.Hilk
    Moderators
    wrote on 11 Apr 2019, 05:33 last edited by J.Hilk 4 Nov 2019, 05:35
    #7

    @PetQter ok, the connect is indeed added twice in the moc file. on 2nd look, they are named slightly different and therefore shouldn't interfere with each other.

    Very strange, what version of QtCreator are you using?

    Is this still the case, if you clean your project, rerun qmake and rebuild?

    The easiest way to solve this is, not using the connect by name feature. But connecting the the signals of your UI elements with slots in cpp via Object::connect calls


    Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


    Q: What's that?
    A: It's blue light.
    Q: What does it do?
    A: It turns blue.

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    • P Offline
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      PetQter
      wrote on 11 Apr 2019, 05:59 last edited by
      #8

      And what about described Sleep() behavior with limit 40ms ? I have suspicion that problem is somewhere in internals where is triggered press button event and this code does not wait to release button and detect pressed button again. It is only way how can I explain correct behavior when Sleep(milisec) is for longer time than 40ms.

      Second thing - the same behavior I have when created new widgets application and put to main window only one push button and create auto-connected slot.

      J 1 Reply Last reply 11 Apr 2019, 06:15
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      • P Offline
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        PetQter
        wrote on 11 Apr 2019, 06:03 last edited by
        #9

        0_1554962615246_About.jpg

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        • P PetQter
          11 Apr 2019, 05:59

          And what about described Sleep() behavior with limit 40ms ? I have suspicion that problem is somewhere in internals where is triggered press button event and this code does not wait to release button and detect pressed button again. It is only way how can I explain correct behavior when Sleep(milisec) is for longer time than 40ms.

          Second thing - the same behavior I have when created new widgets application and put to main window only one push button and create auto-connected slot.

          J Offline
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          J.Hilk
          Moderators
          wrote on 11 Apr 2019, 06:15 last edited by
          #10

          @PetQter said in Slot called twice when button pressed:

          And what about described Sleep() behavior with limit 40ms ?

          signals aren't processed during sleep calls, so that is expected.

          Like I said, try doing the connects by hand,

          The connect by name functionality should be removed anyway, imho


          Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


          Q: What's that?
          A: It's blue light.
          Q: What does it do?
          A: It turns blue.

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          • P Offline
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            PetQter
            wrote on 11 Apr 2019, 07:19 last edited by
            #11

            I created new pushButton_2 and added: to MainWindow constructor:

            QObject::connect(ui->pushButton_2, SIGNAL(pressed()), this, SLOT(pushButton_2_slot()));
            
            The result is the same, after click on pushButton_2 slot is called two times.
            
            J 1 Reply Last reply 11 Apr 2019, 07:39
            0
            • P PetQter
              11 Apr 2019, 07:19

              I created new pushButton_2 and added: to MainWindow constructor:

              QObject::connect(ui->pushButton_2, SIGNAL(pressed()), this, SLOT(pushButton_2_slot()));
              
              The result is the same, after click on pushButton_2 slot is called two times.
              
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              J.Hilk
              Moderators
              wrote on 11 Apr 2019, 07:39 last edited by
              #12

              @PetQter

              ok, let's check if your mouse input is somehow messed up.

              add the following in your constructor:

              QPushButton *btn = new QPushButton();
                  btn->show();
              
                  QObject::connect(btn, &QPushButton::pressed, btn, [=]()->void{qDebug() << "pressed" << QTime::currentTime();});
                  QObject::connect(btn, &QPushButton::released, btn, [=]()->void{qDebug() << "released" << QTime::currentTime();});
                  QObject::connect(btn, &QPushButton::clicked, btn, [=]()->void{qDebug() << "clicked" << QTime::currentTime();});
              

              you'll have to eventually include

              #include <QDebug>
              #include <QTime>
              #include <QPushButton>

              if it's not found.

              This will create a standalone QpushButton that is shown and print mouse events to the QtCreator console.

              you should see something like this

              pressed QTime("09:35:33.590")
              released QTime("09:35:33.721")
              clicked QTime("09:35:33.721")

              once for each mouse click on the button


              Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


              Q: What's that?
              A: It's blue light.
              Q: What does it do?
              A: It turns blue.

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              • P Offline
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                PetQter
                wrote on 11 Apr 2019, 12:03 last edited by
                #13

                @J.Hilk said in Slot called twice when button pressed:

                It seems to be ok, for example after last three clicks:

                pressed QTime("14:01:05.558")
                released QTime("14:01:05.636")
                clicked QTime("14:01:05.636")
                pressed QTime("14:01:13.449")
                released QTime("14:01:13.559")
                clicked QTime("14:01:13.559")
                pressed QTime("14:01:15.684")
                released QTime("14:01:15.809")
                clicked QTime("14:01:15.809")

                J 1 Reply Last reply 12 Apr 2019, 11:18
                0
                • P PetQter
                  11 Apr 2019, 12:03

                  @J.Hilk said in Slot called twice when button pressed:

                  It seems to be ok, for example after last three clicks:

                  pressed QTime("14:01:05.558")
                  released QTime("14:01:05.636")
                  clicked QTime("14:01:05.636")
                  pressed QTime("14:01:13.449")
                  released QTime("14:01:13.559")
                  clicked QTime("14:01:13.559")
                  pressed QTime("14:01:15.684")
                  released QTime("14:01:15.809")
                  clicked QTime("14:01:15.809")

                  J Offline
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                  J.Hilk
                  Moderators
                  wrote on 12 Apr 2019, 11:18 last edited by J.Hilk 4 Dec 2019, 11:57
                  #14

                  @PetQter
                  I'm afraid, than it very well may be something inside your code.

                  To nail it down on your particular project, I would suggest the following.

                  Create a new QWidget project. In the automatically created form layout add a single button.

                  inside the constructor of the form class (Most likely named MainWindow, if it's default)

                  add the same connects.

                  QObject::connect(ui->pushButton, &QPushButton::pressed, btn, [=]()->void{qDebug() << "pressed" << QTime::currentTime();});
                      QObject::connect(ui->pushButton, &QPushButton::released, btn, [=]()->void{qDebug() << "released" << QTime::currentTime();});
                      QObject::connect(ui->pushButton, &QPushButton::clicked, btn, [=]()->void{qDebug() << "clicked" << QTime::currentTime();});
                  

                  If it's also only printing once per click than it's something inside your code.


                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                  Q: What's that?
                  A: It's blue light.
                  Q: What does it do?
                  A: It turns blue.

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                  • P Offline
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                    PetQter
                    wrote on 22 Apr 2019, 21:57 last edited by
                    #15

                    I created new project with button in MainWindow before my last post because I wanted to exclude if it is something in my code. Result is the same.
                    Try please to comment both connect with released and clicked events and leave only connect with pressed handler and put breakpoint into pressed handler. Does not stops your code on breakpoint two times ?
                    Try it please pushing button several times, in my case on first attempt it stops once and after F5 (continue) it does not stop again. But on several next attempts on every click it stops on breakpoint and after continue it stops on breakpoint second time.

                    J 1 Reply Last reply 23 Apr 2019, 05:27
                    0
                    • mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on 22 Apr 2019, 22:06 last edited by
                      #16

                      Hi
                      Only stops once here pr click. No matter how many times i click and f5.

                      alt text

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                      • P PetQter
                        22 Apr 2019, 21:57

                        I created new project with button in MainWindow before my last post because I wanted to exclude if it is something in my code. Result is the same.
                        Try please to comment both connect with released and clicked events and leave only connect with pressed handler and put breakpoint into pressed handler. Does not stops your code on breakpoint two times ?
                        Try it please pushing button several times, in my case on first attempt it stops once and after F5 (continue) it does not stop again. But on several next attempts on every click it stops on breakpoint and after continue it stops on breakpoint second time.

                        J Offline
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                        J.Hilk
                        Moderators
                        wrote on 23 Apr 2019, 05:27 last edited by J.Hilk
                        #17

                        @PetQter
                        works fine for me
                        https://vimeo.com/user97690670/review/331922108/c1f17dd078


                        just tested it with pressed, same behavior as clicked in the video


                        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                        Q: What's that?
                        A: It's blue light.
                        Q: What does it do?
                        A: It turns blue.

                        1 Reply Last reply
                        2
                        • P Offline
                          P Offline
                          PetQter
                          wrote on 24 Apr 2019, 05:28 last edited by
                          #18

                          I believe you. On my side it is probably depending on some internal dll responsible for events like mouse pressed. Maybe combination of Qt library, QtCreator version and Win 10 version. I must check it on another Windows developer's machine but it takes some days to have opportunity. I'd like to know if it has the same problem. I will write result to this post then.

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                          • K Offline
                            K Offline
                            KidTrent
                            wrote on 18 Oct 2020, 19:28 last edited by
                            #19

                            Sorry for the necro, but I was having this same issue and I discovered it was because I was inheriting from another QDialog that I had made. Figured I would post and explain the issue...

                            Steps to reproduce...

                            • Make a base QDialog (let's call it BaseDialog).
                            • Add a button to BaseDialog.
                            • In QtDesigner, right click the button and click "Go to slot"->"clicked(bool)".
                            • Add some debugging to the created slot so you can see it is being hit (qDebug("Slot Hit");).
                            • Make another QDialog (SecondaryDialog).
                            • Force SecondaryDialog to inherit from BaseDialog instead of QDialog (just edit the .h file of SecondaryDialog).
                            • Create an instance of SecondaryDialog programmatically.
                            • Run your program and click the button inside SecondaryDialog, it will be hit twice...

                            I managed to solve this by manually adding the connect call in the BaseDialog constructor instead of depending on Qt to do it for me...

                            JonBJ 1 Reply Last reply 18 Oct 2020, 22:04
                            2
                            • Christian EhrlicherC Online
                              Christian EhrlicherC Online
                              Christian Ehrlicher
                              Lifetime Qt Champion
                              wrote on 18 Oct 2020, 20:53 last edited by
                              #20

                              Please provide a minimal, compilable example of the issue. You for sure did the connect twice.

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                              • K KidTrent
                                18 Oct 2020, 19:28

                                Sorry for the necro, but I was having this same issue and I discovered it was because I was inheriting from another QDialog that I had made. Figured I would post and explain the issue...

                                Steps to reproduce...

                                • Make a base QDialog (let's call it BaseDialog).
                                • Add a button to BaseDialog.
                                • In QtDesigner, right click the button and click "Go to slot"->"clicked(bool)".
                                • Add some debugging to the created slot so you can see it is being hit (qDebug("Slot Hit");).
                                • Make another QDialog (SecondaryDialog).
                                • Force SecondaryDialog to inherit from BaseDialog instead of QDialog (just edit the .h file of SecondaryDialog).
                                • Create an instance of SecondaryDialog programmatically.
                                • Run your program and click the button inside SecondaryDialog, it will be hit twice...

                                I managed to solve this by manually adding the connect call in the BaseDialog constructor instead of depending on Qt to do it for me...

                                JonBJ Offline
                                JonBJ Offline
                                JonB
                                wrote on 18 Oct 2020, 22:04 last edited by
                                #21

                                @KidTrent
                                Most times people say slot hit multiple times turns out they have multiple connects. Not great idea to use the "named" auto-connections from Creator.

                                Oh, I see @Christian-Ehrlicher has written this. Post an example.

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                                • SGaistS SGaist
                                  10 Apr 2019, 19:36

                                  Hi,

                                  Did you check that you are not connecting that signal twice ?

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                                  Rohit_Athithya
                                  wrote on 17 May 2024, 07:24 last edited by
                                  #22

                                  @SGaist I had done the same mistake of connecting the signal to a slot twice. I used pyqt5, and I had used the connect twice! Thus, calling the same message box element twice!

                                  SGaistS 1 Reply Last reply 17 May 2024, 16:49
                                  0
                                  • R Rohit_Athithya
                                    17 May 2024, 07:24

                                    @SGaist I had done the same mistake of connecting the signal to a slot twice. I used pyqt5, and I had used the connect twice! Thus, calling the same message box element twice!

                                    SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on 17 May 2024, 16:49 last edited by
                                    #23

                                    @Rohit_Athithya some things are meant to happen 😁
                                    Glad you found the trick.

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                                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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